The present invention relates to a method of manufacturing a cylindrical electrophotographic photoconductor having a photosensitive drum including a photosensitive layer and a flange for supporting a center shaft, in which the flange is interfitted through an adhesive to an opening end portion of the photosensitive drum. The invention also relates to a method of detecting the adhesive at the opening end portion of the photoconductor.
In the electrophotographic apparatuses that employ an electrophotographic photoconductor, copiers, to which the photoconductors first were applied, were mainly used practically in the early time. In addition to the copiers, laser printers and facsimile machines have now been widely spread as major applications due to the excellent characteristics including high image quality, high quality, and low noise, and the application range is rapidly expanding.
An electrophotographic photoconductor applied to such an electrophotographic apparatus includes a photosensitive drum, in which a photosensitive layer containing a photoconductive material is formed on an outer surface of a cylindrical conductive substrate or a drum, and a flange that supports a center shaft and is interfitted to the opening end portion of the photosensitive drum to transmit rotational driving force from the apparatus to the photosensitive drum.
For the conductive substrate or a drum, aluminum or aluminum alloy with a cylindrical shape, or a cylindrical resin provided with certain conductivity is used.
The photosensitive layer containing photoconductive material formed on the outer surface of the drum was generally composed of a vapor deposited film of photoconductive inorganic material, such as selenium or selenium alloy in the early period. Because the selenium material was considered about its toxicity, for preventing such a fear and from the view point of pursuit of diversity in characteristics and functions, searching for variety of substances, and aiming at reduction of cost, organic photoconductive materials have been rigorously researched.
From the researches, many kinds of photoconductive organic materials have been found including bisazo compounds, phthalocyanine compounds, hydrazone compounds and amine compounds.
From those materials, a material meeting the required characteristic is selected, and while combining with a resin material, dispersed or dissolved in a solvent to obtain a coating liquid. The coating liquid is dip-coated on the outer surface of the above-described drum to form a single-layer or laminated-layer coating film. Such a coating film has become widely employed for an organic photosensitive layer.
The photosensitive drum having such an organic photosensitive layer is mounted on an electrophotographic apparatus, such as a copier or a printer, with a mechanism that allows turning by receiving rotational driving force from the side of the apparatus. On the side of the photosensitive drum, a flange fitted to the opening end portion of the drum serves a function to transmit the rotational driving force to the drum. Accordingly, the flange has a gear on the periphery thereof and a center hole supporting a center shaft.
For assuring this mechanism of transmitting the rotational driving force served by the flange, it is important for the flange and for the photosensitive drum to turn without slip therebetween and to be connected securely together for a long time. Consequently, the flange and the photosensitive drum are usually joined with an adhesive to secure the connection surviving for a long period.
FIG. 2 is an illustration of a photosensitive drum having a photosensitive layer 1xe2x80x941. An adhesive 3 is applied to an opening end portion 2 of the photosensitive drum 1 by providing the adhesive to the predetermined region with a height or thickness from the tip of an adhesive dispenser 4.
Because the photosensitive drums of the electrophotographic photoconductors have various diameters or lengths, and the flanges also have various shapes depending on the types of the photoconductors, the position and the applied configuration of the adhesive must be adjusted according to the dimensions of the photoconductors. Consequently, the discharge from the dispenser is controlled for each of the photosensitive drums so that the depth from the end of the drum and application length in the circumferential direction are adjusted to proper values. The adhesive application in the circumferential direction is effectively performed by turning the photosensitive drum. The circumferential adhesive application to the inside of the opening end portion by discharging from the dispenser is not conducted to the complete perimeter since a grounding plate is required to be conductively contacted to the substrate as described later. The circumferential length of the adhesive is usually xc2xd or ⅓ of the perimeter according to requirement.
FIG. 3 is an illustration showing a flange attached to an electrophotographic photoconductor in an embodiment of the present invention. The main part of the flange 5 is made of a resin material and formed by injection molding to have a gear 6 on the periphery and a center hole 7 in the center for supporting a center shaft 9.
Rotational driving force is transmitted from the side of the apparatus through the gear 6 to the photosensitive drum. A grounding plate 8 made of an elastic metal material is attached to the flange 5. The grounding plate 8 makes the photosensitive drum electrically contacting the center shaft 9 made of a rigid metal, such as stainless steel, and functions to ground the charge carriers generated on the side of the photosensitive drum to the side of the apparatus. The flange 5 is fitted into the photosensitive drum with the side of the grounding plate 8 facing the drum. At that time, if the position on the side of the photosensitive drum corresponding to the position of the contact point 12 of the grounding plate 8 is applied with adhesive, then it often causes defective electrical conductivity. Therefore, an area without adhesive application is necessary to be conserved on the inside of the opening end portion 2 of the photosensitive drum.
However, when the adhesive is applied to the inside of the opening end portion of the photosensitive drum, it is unavoidable to have some abnormal state of departing from the designed shape of the adhesive, such as unapplied region, ununiformity, blur, and deviated position of the applied adhesive. If the photoconductor is manufactured in such an abnormal adhesion state between the photosensitive drum and the flange, and is mounted on an electrophotographic apparatus to operate the apparatus, the joint strength between the flange and the photosensitive drum can occasionally not withstand the rotational driving force received by the drum, and the joint may break resulting in failure of apparatus"" function. When the adhesive used in the joint is transparent, in particular, like a commercially available instant adhesive, a detection method that takes advantage of difference in reflectivity between the substrate and the adhesive surface using an optical fiber sensor with a red LED, can not exactly detect the adhesive, thus, visual observation of the applied condition is indispensable. The visual observation is made periodically, not continuous from the viewpoint of production cost.
Here, the abnormal state of the applied adhesive slowly develops in usual, so the periodical visual observation is liable to delay notice of the abnormal state. When the abnormal state is found, the products often have already proceeded to the next fitting step. In such a case, it is necessary to go back the production steps and to conduct destructive inspection for selecting defective products. This kind of detection method is inferior in operating performance and in economy, and adversely affected productivity of a photoconductor.
The present invention has been made in view of the above-described problem, and an object of the invention is to provide a method of manufacturing a cylindrical electrophotographic photoconductor, wherein the method allows to detect, indicate and judge the applied condition of an adhesive including a transparent adhesive without contact, with high accuracy and high speed, and also to confirm measured records. By making sure the selection of the product that is defective in applied condition of the adhesive, the detachment of the flange from the electrophotographic photoconductor in use is prevented for a long period.
Another object of the invention is to provide a method of detecting an adhesive at the opening end portion of a cylindrical electrophotographic photoconductor.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In a method of manufacturing a cylindrical electrophotographic photoconductor having a photosensitive drum and a flange that supports a center shaft and is fitted to the inside of an opening end portion of the photosensitive drum, the object of the invention is accomplished by the method comprising a step of detecting the adhesive using a CCD laser displacement sensor after applying the adhesive to the opening end portion and before fitting the drum with the flange.
Advantageously, the height of the adhesive is measured with the displacement sensor in the step of detecting the adhesive of the manufacturing method.
Advantageously, the measurement of the height of the adhesive is conducted by scanning the displacement sensor in an axial direction in the step of detecting the adhesive of the manufacturing method.
Advantageously, in the step of detecting the adhesive of the manufacturing method, a shape of the applied adhesive is detected by using the CCD laser displacement sensor after applying the adhesive to the opening end portion and before fitting the drum with the flange.
Advantageously, in the step of detecting the adhesive of the manufacturing method, detecting the shape of the applied adhesive is conducted by turning the photosensitive drum while scanning the displacement sensor in the axial direction.
Advantageously, the adhesive applied to the opening end portion is a transparent adhesive in the method of manufacturing the cylindrical electrophotographic photoconductor.
Further, a method for detecting an adhesive at an opening end portion of the present invention, in a step for detecting the adhesive using a CCD laser displacement sensor after applying the adhesive to the opening end portion and before fitting the drum with the flange, comprises a process of judging the presence or absence of the adhesive by taking the region without the adhesive as a base for a height measurement and making a height higher than the base by a certain value to be a threshold level.
The detection of the adhesive using the CCD displacement sensor in the present invention is conducted by determining the basic height at the base position and by measuring the adhesive height every moment while moving the sensor in the axial direction of the photosensitive drum or simultaneously turning the drum, to obtain a chart plotted in two dimensions or three dimensions with the abscissa being the axial position in the drum and the ordinate being the height or thickness of the adhesive. Here, for accurate judgement of the presence or absence of the adhesive, it is preferable to take the difference between the base position and the height of the internal surface of the drum at the interior side with respect to the applied adhesive as a threshold value in order to compensate for slant of the drum axis from the horizontal axis.